The invention relates to a coupling for resilient interconnection of two objects, especially a wheel axle housing and a chassis of a vehicle, comprising
an internal coupling device comprising a supporting piece, which extends in an axial direction and has an axial supporting piece portion,
a rubber-elastic element, which is arranged round the supporting piece portion and has an axially extending outer surface and two substantially radially extending end surfaces, and
an external coupling device comprising two, approximately cup-shaped abutment members with a tubular wall portion and a bottom portion defining an inner portion of the abutment member, where each wall portion has an inner surface arranged to extend along and radially outside respective end portions of the outer surface of the element, the end of the wall portion facing away from the bottom has an end surface, and an inside of each bottom portion facing the inner portion of the abutment member are each arranged to abut against an end surface of the element for axial compression thereof, while the abutment members are pushed towards each other.
In U.S. Pat. No. 3,030,132 a coupling is disclosed where a body of a rubber-elastic material is cast between coupling devices or members during the actual assembly of the coupling. In order to ensure that the material is adequately compressed, during the casting process a recess is formed in the body while the cup members are kept at a correct distance apart. This is a laborious method, which is unsuitable for modern, fast serial production of vehicles. There is no indication of how a correct centring of the two cup members relative to each other is achieved during casting. A correct relative positioning of the cup members and the internal ball surface also seems to be important in order to ensure that the rubber-elastic material is not pinched between the cup members or that this material completely fills the space between the cup members and the interior ball surface 1. This is also important to ensure that the coupling obtains the correct spring characteristic.
U.S. Pat. No. 6,231,264 illustrates a bearing device for a torque rod where an intermediate sleeve may be provided inside eyelets forming end portions of arms. In the intermediate sleeve is provided a bearing sleeve. The eyelets are not arranged to provide an axial compression of the bearing sleeve. The intermediate sleeve is only provided in order to create an axially fixed connection between the bearing sleeve and the eyelets, since the intermediate sleeve may be axially secured to the bearing sleeve on one side and on the other side to the eyelets via snap rings. The function of the intermediate sleeve is not for centring the eyelets or for counteracting the penetration of material of the bearing device between the eyelets, and it has a row of circular grooves that weaken it.
In U.S. Pat. No. 5,649,719 an assembly is illustrated comprising a wheel axle housing and a chassis of a vehicle, and a coupling of the above-mentioned type for interconnecting the wheel axle housing and the chassis. FIG. 1 is a perspective view of the assembly, where components have been separated from one another, and FIG. 2 illustrates a longitudinal section through the coupling.
As illustrated in FIG. 1, a first end portion 6, 8 of two arms 2, 4 is each connected with a longitudinal frame beam 10 of a vehicle. Second end portions of each arm 2, 4 converge at a coupling 12 located above and in front of a wheel axle housing 14, connecting the arms 2, 4 to the wheel axle housing via a bracket 16.
As illustrated in FIG. 2, the coupling 12 comprises an internal coupling device with an elongated supporting piece 20 with end attachment portions 22, 24 via which the supporting piece can be attached to the wheel axle housing, and a central portion 26, which carries a rubber-elastic element 28.
The element 28 is radially enclosed by an external coupling device, which is fixed to the arms 2, 4 and comprises a first abutment member 30 with a bottom or shoulder 32, and a second abutment member 34, provided in the form of a ring. This ring 34 may be inserted in the first abutment member 30 and prevented from being moved out of it by means of a snap ring 36, which is arranged for insertion in a groove in the first abutment member 30. The shoulder 32 and the ring 34 are arranged to abut against respective opposite end portions 38, 40 of the element 28. In addition to the ring 34, the known coupling comprises an additional ring 42, which is arranged to abut against the shoulder 32, for extra support of the element 28 axially, i.e. in the supporting piece's longitudinal direction.
During operation the coupling is influenced by substantial forces in its longitudinal direction as well as in its transverse direction. There is therefore a need for extremely strong and hence expensive rings, which may have to be forged from steel. When the coupling is assembled, the element 28 is compressed axially by the ring 34 being forced axially by means of a separate tool in the direction of the shoulder 30 or the additional ring 42, whereupon the snap ring 36 is inserted in the groove by expanding radially therein. Compression stresses are thereby advantageously created in the element. During this process it is vital for the snap ring 36 to come into a correct engagement with the groove in order to ensure that the snap ring 36 will not be forced out of the groove under the influence of the highly fluctuating stresses on the coupling 12 during operation of the vehicle.
The object of the invention is to provide a coupling of the above-mentioned type, which is encumbered to a lesser extent by the above-mentioned drawbacks.